VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1929-1932 1949 REAR END

I have a 1949 3600 3/4T with a 216 motor. I am in the process of replacing it with a rebuilt 1954 235 motor. Right now I can get about 40 MPH out of the 216. I think I have the 4.55 ring and pinion gears in the truck (it is a 4 speed). I can climb telephone poles with the truck, but I also tick off a lot of people who are lined up behind me going 40 MPH. Will the 235 allow me to get 50 MPH or will I need to change rear end gears. I was told that a 3.73 set up would be ideal, but I'm not aware of anyone making them anymore. Any ideas?

You might want to also post this in the 1949-54 forum or the Chevy Truck forum since your posting is currently in the 1929-32 forum.

When your truck was new it would do between 65 and 70 MPH (with 15" tires and 4.55)...Thats with the engine peaking out at 3800 RPM.The safe crusing speed would have been around 50-55 MPH or 2800 to 3000 RPM.The 235 engine will have a higher "safe " engine RPM speed , around 3200 RPM. so you could run it at 60 MPH without blowing up.The problem is the truck uses a larger fan blade,has poor firewall insulation and no cloth material inside the cab to absorb noise so the engine will still sound awful busy, especailly if you are accustomed to modern vehicles.
The 3.73 and 4.10 rear ends were used it later 3/4 and 1 ton trucks with automatic transmissions.Either would be a considerable improvement and they are a "bolt in" change.With the 4.10 your RPM's at 60 would be about 2900 and about 2600 with the 3.73.That (the 3.73) would get you up into the 65 MPH crusing range.From my experiance you need about 80MPH to keeps the folks behind you happy.